Messages in this thread | | | Subject | Re: [RFD PATCH 1/4] powerpc: cpu: Reduce the polling interval in __cpu_up() | From | Nathan Lynch <> | Date | Tue, 16 Jun 2009 11:06:45 -0500 |
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Please cc linuxppc-dev if you want the powerpc maintainer to pick this up.
Gautham R Shenoy <ego@in.ibm.com> writes: > The cpu online operation on a powerpc today takes order of 200-220ms. Of > this time, approximately 200ms is taken up by __cpu_up(). This is because > we poll every 200ms to check if the new cpu has notified it's presence > through the cpu_callin_map. We poll every 200ms until the new cpu sets > the value in cpu_callin_map or 5 seconds elapse, whichever comes earlier. > > However, the time taken by the new processor to indicate it's presence has > found to be less than a millisecond
Only with your particular configuration (which is not identified). It can take much longer than 1ms on others.
> Keeping this in mind, reduce the > polling interval from 200ms to 1ms while retaining the 5 second > timeout.
Ack on the patch, but the changelog needs work. I assume your observations are from a pseries system -- please state this in the changelog ("powerpc" is too broad), along with the processor model and whether the LPAR's processors were configured in dedicated or shared mode.
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